Method for conditioning web- or sheetlike material



Sept. 27, 1966 A. ARONSSON 3,274,697

METHOD FOR CONDITIONING WEB- OR SHEET-LIKE MATERIAL Filed March 2, 1964FIG. I.

INVENTORZ ARENT ARONSSON widmwmw ATTYS.

United States Patent 3,274,697 METHOD FOR CONDITIONING WEB- 0R SHEET-LIKE MATERIAL Arent Aronsson, Nacka, Sweden, assignor to AktiebolagetSvenska Flaktfabriken, Stockholm, Sweden Filed Mar. 2, 1964, Ser. No.349,535 7 Claims. (Cl. 34-36) This invention relates to a method forconditioning webor sheet-like material. In the case of hygroscopic weborsheet-like material the conditioning has as its primary object to bringthe moisture ratio into balance with normal storage atmosphere. Wherethe webor sheet-like material comprises paper, such a conditioning ofthe paper is also required with regard to the stability requirements thepaper has to meet for printing and the like. The prior art illustratesmany ways in which conditioning may be carried out, for example 'bysupplying the moisture in a finely divided form, through nozzles or bypassing the material through a chamber having a steam atmosphere.

When applying the first-mentioned method, i.e. by applying moisture vianozzles, difficulties arise in obtaining uniform distribution of themoisture throughout the web, and there is, furthermore, great risk ofstain formation, particularly in material having a sensitive surface.Conditioning in a steam atmosphere on the other hand, includes the riskof stain formation due to partial condensation and renders it, moreover,difficult to carry out the conditioning without an undesirable increasein temperature. The best conditioning method heretofore known is to passthe material through a closed room, where it is exposed to the effect ofmoist air of suitable saturation. This method requires, however, a longtreatment time, due to the temperature increase in the material causedby the moisture condensing therein and the reduction of the relativehumidity of the air resulting therefrom.

The method according to the invention has as its principal object theelimination of the last mentioned disadvantages and is characterized inthat the moisture is supplied to the material by blowing a heated,moist, gaseous medium against one surface of the material while at thesame time blowing a cold, moist gaseous medium against the oppositesurface of the material, thereby continuously conducting away the heatreleased by the condensing moisture. The moisture supplying medium maybe heated moist air or steam. The treatment is preferably carried out inseveral different steps, by providing separate consecutive treatmentswherein the moisture supplying medium is of different condition.

The conditioning may be carried out such, that for each step ortreatment the blowing side for the heated, moist medium and the cold,moist medium respectively is changed. In order to prevent mixing of thesaid two media, the treatment is preferably carried out in an entirelyclosed chamber, the said media being supp-lied such that in said chamberan overpressure is maintained on both sides of the web, and that atleast part of the two media is sucked off from the chamber throughopenings provided along the two side edges of the web.

Other objects and a fuller understanding of the invention may be had byreferring to the following specification and claims taken in conjunctionwith the accompanying drawing in which:

FIG. 1 is a schematic longitudinal sectional view through apparatuswhich may be used to practice the method of the present invention; and

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1 as ifFIG. 1 were not in section.

Referring now to the drawing, a housing or casing 1 for a treatingapparatus, designed as a closed chamber,

is divided into three separate sections A, B and C and provided with afeed opening 2 and a discharge opening 3 for a continuously advancedmaterial 4. During the passage through the chamber a heated, moist,gaseous medium is supplied to the material, which medium according tothe invention is blown against one surface of the material, in theexample shown against the upper surface thereof. The medium is suppliedby means of circulation fans 5, each of said sections including a fan 5driven in the present instance by a directly connected electric motor 6.The fan presses the medium into an air distribution box 7 arranged abovethe web, the surface of the box facing the web being provided with aplurality of uniformly spaced air supply openings 8. The medium blownagainst the web is returned to the circulation fan through a pluralityof exhaust or discharge passages designed as tubes 9, which pass throughthe said air distribution box and open into a suction chamber 10communicating with the inlet of the fan. As illustrated in FIG. 2, forheating and, if required, humidifying the treating medium, means 11 areprovided.

According to the invention, a cold, moist, gaseous medium is blownagainst the opposite surface of the web simultaneously with thesupplying of the heated medium. For this reason, each of the sections isalso equipped with a second circulation fan 12, which is directlyconneeted to a mot-or 13 and forces the cold medium into a distributionbox 14 arranged below the web. In a manner similar to above, thedistribution box 14 is provided with air supply openings 15 and exhaustor discharge passages 16, which open into a suction chamber 17. Thetemperature of the cold medium is controlled by cooling means 18.

As both cold and warm media is supplied simultaneously to opposite sidesof the web, means must be provided to prevent inadvertent mixing of themedia by passing around the longitudinal edges of the web. To this endit is advisable that at least a part of the two media is discharged orsucked off from the chamber through openings provided along the twolongitudinal edges of the web. As illustrated in FIG. 2, shield bars 19on both sides of the web edges prevent mixing of the two separatelysupplied media. The said bars are preferably designed such, that theyform a longitudinal passage for sucking off a small part of each of themedia.

Although the invention has been described with a certain degree ofparticularity, it is understood that the present disclosure has beenmade only by way of example, and that numerous changes in the apparatusutilized in carrying out the method may be made without departing fromthe spirit and the scope of the invention as hereinafter claimed.

What I claim is:

1. A method of conditioning web or sheet-like material in a. chambercomprising the steps of: feeding the material to be treated through saidchamber, blowing a heated, moist, gaseous medium against one surface ofthe material, blowing a cold, moist, gaseous medium against the oppositesurface of said material to thereby conduct away the heat released bythe condensation of moisture in and on the material.

2. A method in accordance with claim 1 wherein the heated, moist,gaseous medium comprises heated, moist air.

3. A method in accordance with claim 1 wherein the heated, moist,gaseous medium comprises steam.

4. A method in accordance with claim 1 including the steps of dividingthe chamber into at least two sections, and supplying the heated, moist,gaseous medium in each of said sections at different conditions.

5. A method in accordance with claim 1 including the step of-dischargingat least a portion of the two media from the chamber at points closelyadjacent the longitudinal edges of the material.

6. A method of conditioning Web or sheet-like material in asubstantially closed chamber, comprising the steps of: dividing thechamber into at least two sections, feeding the material through saidsections consecutively, supplying moitsure to the material in eachsection by blowing heated, moist, gaseous medium against one surface ofthe material in one of said sections and against the opposite surface inthe other of said sections, and simultaneously therewith blowing cold,moist, gaseous medium against the opposite surface of said material insaid one section and the surface of said material in the other of saidsections.

7. A method of conditioning web or sheet-like material in asubstantially closed chamber, comprising the steps of: dividing thechamber into at least two sections, feeding the material through saidsections consecutively, supplying moisture to the material in eachsection by blow- References Cited by the Examiner UNITED STATES PATENTS2,123,341 7/1938 Often 34-13 X 2,297,314 9/1942 Offen 34-37 X 2,682,1166/1954 Dungler 3437 X FREDERICK L. MATTESON, IR., Primary Examiner.

JOHN J. CAMBY, Examiner.

1. A METHOD OF CONDITIONING WEB OR SHEET-LIKE MATERIAL IN A CHAMBERCOMPRISING THE STEPS OF: FEEDING THE MATERIAL TO BE TREATED THROUGH SAIDCHAMBER, BLOWING A HEATED, MOIST, GASEOUS MEDIUM AGAINST ONE SURFACE OFTHE MATERIAL, BLOWING A COLD, MOIST, GASEOUS MEDIUM AGAINST THE OPPOSITESURFACE OF SAID MATERIAL TO THEREBY CONDUCT AWAY THE HEAT RELEASED BYTHE CONDENSATION OF MOISTURE IN AND ON THE MATERIAL.